way or another is scant. Over the course of the Middle English period, sound shifts in the language meant that the (-ende) participle ending and the (-unge) gerund ending merged into a new ending, (-ing). This change, which was complete in southern England around the late fifteenth century and spread north from there, rendered participles and gerunds indistinguishable. It is at this point that a sudden increase in the use of progressive forms is visible, though they would not take their current form until the eighteenth century. Herbert Schendl has concluded that "with this feature, a polygenetic origin ... seems attractive, and at least the further extension of the progressive is a language-internal development." Do-periphrasis in a variety of uses. Modern English is dependent on a semantically neutral 'do' in some negative statements and questions, e.g. 'I don't know' rather than 'I know not". This feature is linguistically very rare, although all West Germanic languages except Afrikaans can use "do" as an auxiliary. Celtic languages use a similar structure, but without dependence. The usage is frequent in Cornish and Middle Cornish – e.g. "Omma ny wreugh why tryge", "You do not stay here" – and it is used in Middle Breton. "Do" is more common in Celtic Englishes than Standard English. There are, however, other theories for how this feature developed in standard English. The key difficulty in explaining this form as a Brittonicism is its late appearance in the language—arising in the fifteenth century. Thus, several linguists have proposed that it developed independently during the transition between Middle and Early Modern English.. Various possible Brittonicisms Loss of weorþan In Old English, a common verb weorþan existed (cognate with Dutch worden and German werden) where today motion verbs like go and went are used instead, e.g., "What shall worthe of us twoo!" This use of motion verbs occurs in Celtic texts with relative frequency e.g. "ac am hynny yd aeth Kyledyr yg gwyllt" = "and because of this Kyledyr went mad" (Middle Welsh, where aeth = 'went').. Rise in use of some complex syntactic structures English construction of complex sentences uses some forms which in popularity may suggest a Celtic influence. Clefting in Old Welsh literature precedes its common use in English by perhaps 400 years – depending on the dating of Welsh texts. Cleft constructions are more common in Breton French than Standard French and more common and versatile